This invention relates to thermal ink jet printing and, more particularly, to a cleaning and priming station where the printhead nozzle faces are cleaned by a rotary cleaning device.
The ink jet printing system may be incorporated in either a carriage type printer or a pagewidth type printer. The carriage type printer generally has a relatively small printhead containing the ink channels and nozzles. The printhead is usually sealingly attached to a disposable ink supply cartridge and the combined printhead and cartridge assembly is reciprocated to print one swath of information at a time on a stationarily held recording medium, such as paper. After the swath is printed, the paper is stepped a distance equal to the height of the printed swath, so that the next printed swath will be contiguous therewith. The procedure is repeated until the entire page is printed. In contrast, the pagewidth printer has a stationary printhead having a length equal to or greater than the width of the paper. The paper is continually moved past the pagewidth printhead in a direction normal to the printhead length and at a constant speed during the printing process.
Thermal ink jet printing devices, because of the close tolerances between the recording medium and the printhead nozzles and the small size of the nozzles themselves, require periodic cleaning of the printhead nozzle faces due to the buildup of recording medium fibers, dust, and ink which builds up theron. Most of the ink and debris are removed from the vicinity of the nozzles during the priming operation in which ink is either drawn under a vacuum from the nozzles at the priming station, or ink is forced from the nozzles under pressure at the priming station. However, any partially or fully dried ink and any contamination debris within the vicinity of the nozzles will produce a directionality problem with the ejected droplets. Therefore, the nozzle face of the printhead must be cleaned to enable commercially acceptable printed documents by the printers. Numerous configurations of nozzle face cleaning devices are known for removing collected ink and other contaminates from the nozzle faces of the printhead, such as, by use wipers and blades and the like, but all impose some constraints or compromise which impacts the printer cost, size, or printer operation.
U.S. Pat. No. 4,935,753 to Lehmann et al discloses an apparatus for cleaning the nozzle surface of an ink jet printhead. The apparatus comprises wiping lips which are wedge shaped and located on an endless belt which rotates on two rollers. A band cleaning device, preferably using spiral wiping edges, is located under the endless belt for cleaning ink from the endless belt and the wiping lips.
U.S. Pat. No. 4,371,881 to Bork et al discloses a pivotal ink shield for the writing head of an ink recording device. The shield is movable relative to the writing head opening to shield, wipe, and flush writing head outlets.
Copending U.S. patent application entitled "A Clean Printhead Cleaner", U.S. Ser. No. 07/528,765 to Markham, filed May 25, 1990, and commonly assigned to the assignee of the present invention discloses a rotary cleaning device for periodically cleaning ink jet printhead nozzles. A rotary cleaning device has at least one flexible wiping blade which is attached to a rotatable support. The rotatable support is attached to a shaft which is rotatably driven by a dedicated motor or connected through linkages to be driven off other motors already existing in a printer. A rotary support is preferably cylindrical and the flexible wiping blade preferably mounted thereon following a helical path along the surface thereof. A cleaning device also includes a means for cleaning the blade to remove any ink or other contaminates from the blade in order to prevent deterioration of the cleaning quality of the wiping blade. A wet type washing blade may also be added to provide a means for washing the printhead nozzle face with a solvent prior to wiping by the blade to aid in removal of any dried ink.